/*
 * EventNode.java January 2010
 *
 * Copyright (C) 2010, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.stream;

/**
 * The <code>EventNode</code> object is used to represent an event
 * that has been extracted from the XML document. Events provide a
 * framework neutral way to represent a token from the source XML.
 * It provides the name and value of the event, if applicable, and
 * also provides namespace information. Some nodes will have
 * associated <code>Attribute</code> objects, typically these will
 * be the XML element events. Also, if available, the event will
 * provide the line number the event was encountered in the XML.
 *
 * @author Niall Gallagher
 * @see wx.xml.simpleframework.xml.stream.EventReader
 */
interface EventNode extends Iterable<Attribute> {

    /**
     * This is used to provide the line number the XML event was
     * encountered at within the XML document. If there is no line
     * number available for the node then this will return a -1.
     *
     * @return this returns the line number if it is available
     */
    int getLine();

    /**
     * This provides the name of the event. Typically this will be
     * the name of an XML element if the event represents an element.
     * If however the event represents a text token or an element
     * close token then this method may return null for the name.
     *
     * @return this returns the name of this event or null
     */
    String getName();

    /**
     * This returns the value of the event. Typically this will be
     * the text value that the token contains. If the event does
     * not contain a value then this returns null. Only text events
     * are required to produce a value via this methods.
     *
     * @return this returns the value represented by this event
     */
    String getValue();

    /**
     * This is used to acquire the namespace reference that this
     * node is in. A namespace is normally associated with an XML
     * element or attribute, so text events and element close events
     * are not required to contain any namespace references.
     *
     * @return this will provide the associated namespace reference
     */
    String getReference();

    /**
     * This is used to acquire the namespace prefix associated with
     * this node. A prefix is used to qualify an XML element or
     * attribute within a namespace. So, if this represents a text
     * event then a namespace prefix is not required.
     *
     * @return this returns the namespace prefix for this event
     */
    String getPrefix();

    /**
     * This is used to return the source of the event. Depending on
     * which provider was selected to parse the XML document an
     * object for the internal parsers representation of the event
     * will be returned. This is useful for debugging purposes.
     *
     * @return this will return the source object for this event
     */
    Object getSource();

    /**
     * This is true when the node represents an element close. Such
     * events are required by the core reader to determine if a
     * node is still in context. This helps to determine if there
     * are any more children to be read from a specific node.
     *
     * @return this returns true if the event is an element close
     */
    boolean isEnd();

    /**
     * This is true when the node represents a new element. This is
     * the core event type as it contains the element name and any
     * associated attributes. The core reader uses this to compose
     * the input nodes that are produced.
     *
     * @return this returns true if the event represents an element
     */
    boolean isStart();

    /**
     * This is true when the node represents a text token. Text
     * tokens are required to provide a value only. So namespace
     * details and the node name will typically return null.
     *
     * @return this returns true if this represents text
     */
    boolean isText();
}